Apparatus for dosing a constant quantity of fluid into an analysis device

Abstract

In an apparatus for the discontinuous dosing of a constant quantity of fluid into an analysis device, the fluid feed system is connected by means of a three-way valve on the one hand via the dosing valve and a shut off valve arranged downstream and on the other hand via a by-pass to the fluid discharge system. A compressed air source for the production of a constant air pressure is connected between the three-way valve and the dosing valve. All the components of the system are controlled by a programme control unit, so that the fluid flow through the dosing valve is temporarily interrupted by closing the shut off valve and switching over the fluid feed to the by-pass and at the same time releasing the connection of the compressed air to the dosing valve. Thereafter the compressed air source is switched off by the control unit and the interruption of the fluid flow at the dosing valve is cancelled.

What we claim is: 
     
       1. An apparatus for the discontinuous dosing of a constant quantity of a fluid into an analysis device, comprising a dosing valve through which the fluid to be analysed flows, a three-way valve connecting an inlet for the fluid either through the dosing valve and a first shut-off valve connected downstream of the dosing valve, or through a by-pass conduit, to an outlet for the fluid, a source of compressed gas for the production of a constant gas pressure connected via a second shut-off valve to a conduit connected between the three-way valve and the first shut-off valve, and a programme control device connected to the dosing valve, the first and second shut-off valves and the three-way valve, the programme control device, when in use, during a dosing process, temporarily interrupting the fluid flow through the dosing valve by closing the first shut-off valve and switching the three-way valve to the by-pass conduit and connects the source of compressed gas to the conduit between the three-way valve and the first shut-off valve, so that the quantity of fluid contained between the three-way valve and the first shut-off valve is under the gas pressure during the dosing process, whereafter the second shut-off valve is closed and the fluid flow through the dosing valve is resumed. 
     
     
       2. An apparatus as claimed in claimed 1, wherein the source of compressed gas comprises an air pressure regulator and an adjusting valve.